CN114751887A - Synthetic method of cyclic ethane carbonic ester - Google Patents

Abstract

The invention relates to a method for synthesizing ethylene carbonate, which takes a reaction rectifying tower as a reaction site, dimethyl carbonate and ethylene glycol are subjected to ester exchange continuously in the reaction rectifying tower under the action of a catalyst to obtain methanol at the tower top, and a mixture of the ethylene glycol, the ethylene carbonate and the catalyst is extracted at the tower bottom. Then the catalyst is recycled, the cyclic ethane carbonic ester is separated and refined, and the ethylene glycol is recycled. Compared with the prior art, the method has the advantages of simple process flow for separating the catalyst and the product, high production continuity, suitability for large-scale production and equipment cost saving.

Description

A kind of synthetic method of cycloethane carbonate

technical field

The invention belongs to the technical field of chemical industry, in particular to a method for synthesizing cycloethane carbonate.

Background technique

Cycloethane carbonate (EC) is an excellent solvent and organic synthesis intermediate, which is widely used in battery electrolytes, ester intermediates, fibers, pharmaceuticals and organic synthesis industries. The synthesis methods of EC include phosgene method, urea alcoholysis method, ethylene oxide and carbon dioxide addition method, etc. The phosgene method is the earliest method for the industrial preparation of cycloethane carbonate, which has been eliminated due to its highly toxic phosgene and serious environmental pollution. The urea alcoholysis method still has problems such as urea decomposition and difficult recovery of catalysts, and it is still in the research stage. In the ethylene oxide method, the atomic utilization rate of ethylene oxide and carbon dioxide reaches 100%, which is the main process for the industrial production of cycloethane carbonate. However, ethylene oxide is expensive, the production cost is high, and the epoxy Ethane is flammable and explosive and difficult to transport, and industrial production is greatly affected by the origin of raw materials. The transesterification reaction has been paid more and more attention due to its mild reaction conditions and high safety.

Patent CN 109438410 A discloses a MgO/NaY solid base catalyst for synthesizing cycloethane carbonate by transesterification of dimethyl carbonate (DMC) and ethylene glycol (EG). The reaction temperature is 90-120°C, The reaction time is 2-12h, and the catalyst dosage is 5-45% of ethylene glycol. After the catalyst was circulated for five times, the catalyst activity decreased from 94.4% of the first reaction to 91.4%. There were problems such as long reaction time, large amount of catalyst and high price, and the activity of the catalyst needed to be further improved. There is still a need to develop a cost-effective catalytic process for the transesterification synthesis process.

SUMMARY OF THE INVENTION

The purpose of this invention is to provide a kind of new synthetic method of cycloethane carbonate.

The object of the present invention can be realized through the following technical solutions:

The invention provides a method for synthesizing cycloethane carbonate. Using dimethyl carbonate and ethylene glycol as raw materials, cycloethane carbonate is synthesized by a method of transesterification, and methanol is by-produced.

In one embodiment of the present invention, the method specifically includes the following steps:

Taking the reactive distillation column as the reaction place, dimethyl carbonate and ethylene glycol are continuously transesterified in the reactive distillation column under the action of the catalyst, and methanol is obtained at the top of the column, and ethylene glycol and ethylene glycol are extracted from the bottom of the column. A mixture of ethane carbonate and catalyst.

In one embodiment of the present invention, the reactive distillation column is divided into a first section, a second section and a third section from top to bottom, the first section is a rectification section, and the second section and the third section are reaction stage, the raw material ethylene glycol and catalyst are fed from between the first stage and the second stage, and the raw material dimethyl carbonate is fed from between the second stage and the third stage.

In one embodiment of the present invention, the alkali metal alkoxide is dissolved in ethylene glycol or methanol.

In one embodiment of the present invention, the alkali metal of the alkali metal alkoxide is sodium or potassium, and the alcohol is methanol, ethanol or ethylene glycol, preferably methanol or ethylene glycol.

In one embodiment of the present invention, the molar ratio of the raw material ethylene glycol to the dimethyl carbonate entering the reactive distillation column is between 1.0-3.0, preferably 1.3-2.0.

In one embodiment of the present invention, in the reactive distillation column, the molar ratio of alkali metal alkoxide to ethylene glycol is between 1:500 and 1:50, preferably between 1:200 and 1:100.

In one embodiment of the present invention, the method specifically includes the following steps:

(1) catalyst preparation: the alkali metal alkoxide is dissolved in raw material ethylene glycol or methanol to prepare a catalyst material;

(2) transesterification reaction: described raw material ethylene glycol and dimethyl carbonate, and catalyst material respectively enter reactive distillation column through respective feed pump, obtain cycloethane carbonate and methanol by catalytic transesterification reaction, Under the action of rectification, methanol enters the rectification zone upwards, enters the top of the column, returns through the condenser, and obtains high-purity methanol at the top of the column. Alcohol and catalyst form bottoms;

(3) Catalyst recovery cycle: the column bottom material enters the thin-film evaporator, and the ethylene glycol and cycloethane carbonate are quickly evaporated, the catalyst is concentrated, and is pumped to the catalyst configuration step through the catalyst circulation, and is formulated into catalyst materials in proportion ,recycle;

(4) Separation and purification of ethylene carbonate: the steam of ethylene glycol obtained from step (3) and ethylene carbonate enters the separation and purification tower of ethylene carbonate, and obtains high-purity ethylene carbonate at the bottom of the tower Ester, tower top obtains ethylene glycol;

(5) ethylene glycol recycling: the ethylene glycol obtained from step (4) is recycled to the reactive distillation column for recycling.

In one embodiment of the present invention, the reactive distillation column, the thin film evaporator and the cycloethane carbonate separation and purification column are operated under reduced pressure.

In an embodiment of the present invention, the reflux ratio at the top of the rectifying column is 0.1-1, preferably 0.1-0.5.

In an embodiment of the present invention, the bottom operating temperature of the reactive distillation column is 70-130°C, preferably 80-110°C.

Compared with the prior art, the catalyst involved in the method of the invention has high catalytic activity, good stability, high product yield, low price, and can be used repeatedly. The method of the invention has the advantages of simple process flow for separating catalyst and product, high degree of continuous production, suitable for large-scale production and saving equipment cost.

Description of drawings

Fig. 1 is the synthetic process schematic diagram of cycloethane carbonate in the present invention.

Reference numbers in the figure:

1. Ethylene glycol material; 2. Dimethyl carbonate material; 3. Outlet pipeline of catalyst configuration device; 4. Outlet pipeline of ethylene glycol delivery pump; 5. Outlet pipeline of dimethyl carbonate delivery pump; 6 . Catalyst delivery pump outlet pipeline; 7. Reactive rectification tower top material outlet; 8. Reactive rectification tower bottom material outlet; 9. Catalyst circulating pump outlet pipeline; 10. Thin film evaporator tower top material outlet; 11 .The outlet of the bottom material of the thin film evaporator; 12. The ethylene glycol circulation pipeline; 13. The bottom outlet of the cycloethane carbonate separation and purification tower; A1. The ethylene glycol delivery pump; A2. The dimethyl carbonate delivery pump; A3. Catalyst and ethylene glycol mixed liquid delivery pump; A4. Catalyst circulating pump; B. Catalyst configuration tank; R1. Reactive distillation column; R2. Thin film evaporator;

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The present invention provides a kind of synthetic method of cycloethane carbonate, and the technological process refers to Fig. 1, described method specifically comprises the following steps:

(1) catalyst preparation: the alkali metal alkoxide is dissolved in raw material ethylene glycol or methanol to prepare a catalyst material;

(2) transesterification reaction: the ethylene glycol material 1 enters the reactive distillation column R1 through the ethylene glycol delivery pump A1 and the ethylene glycol delivery pump outlet pipeline 4, and the dimethyl carbonate material 2 passes through the dimethyl carbonate The delivery pump A2 and the dimethyl carbonate delivery pump outlet pipeline 5 enter the reactive distillation column R1, and the catalyst material passes through the catalyst configuration device outlet pipeline 3, the catalyst and ethylene glycol mixed solution delivery pump A3 and the catalyst delivery pump outlet pipeline 6 enter the reactive distillation column R1, wherein, the reactive distillation column R1 is divided into the first section, the second section and the third section from top to bottom, the first section is the rectifying section, and the second section and the third section are the reaction stage, the ethylene glycol material and catalyst are fed from between the first and second stages, and the feedstock dimethyl carbonate is fed from between the second and third stages. Ethylene glycol and dimethyl carbonate are catalyzed by transesterification to obtain cycloethane carbonate and methanol. Under the action of rectification, methanol enters the rectification zone upwards, enters the top of the tower, flows back through the condenser, and is subjected to reactive distillation. The tower top material outlet 7 obtains high-purity methanol, the cycloethane carbonate goes down, enters the tower bottom, forms the tower bottom material with excess ethylene glycol and catalyst, and is discharged from the reactive distillation tower tower bottom material outlet 8;

(3) Catalyst recovery cycle: the column bottom material discharged from the column bottom material outlet 8 of the reactive rectification column enters the thin film evaporator R2, and the ethylene glycol and cycloethane carbonate are rapidly evaporated, and the ethylene glycol and cycloethane carbonate vapors are removed from the The material outlet 10 at the top of the thin film evaporator is discharged; the catalyst is concentrated, discharged from the material outlet 11 at the bottom of the thin film evaporator, and sent to the catalyst configuration tank B through the catalyst circulation pump A4 and the catalyst circulation pump outlet pipeline 9, and is formulated in proportion to The catalyst material is circulated to the outlet pipeline 3 of the catalyst configuration device for recycling;

(4) Separation and purification of cyclohexane carbonate: ethylene glycol and cyclohexane carbonate steam discharged from the overhead material outlet 10 of the thin film evaporator enter the cyclohexane carbonate separation and purification tower R3, and obtain high-purity ethylene carbonate at the bottom of the tower. Cycloethane carbonate, high-purity cycloethane carbonate is discharged from the cycloethane carbonate separation and purification tower bottom outlet 13, and the top of the tower obtains ethylene glycol;

(5) ethylene glycol recycling: the ethylene glycol obtained from step (4) is recycled to the reactive distillation column R1 through the ethylene glycol circulation pipeline 12 for recycling.

In the above process method, the molar ratio of the raw material ethylene glycol and dimethyl carbonate entering the reactive distillation column is between 1.0-3.0, preferably 1.3-2.0. The molar ratio of alkali metal alkoxide to ethylene glycol is between 1:500 and 1:50, preferably 1:200 to 1:100. The reactive distillation column, the thin film evaporator and the cycloethane carbonate separation and purification column are operated under reduced pressure. The reflux ratio at the top of the rectifying tower is 0.1-1, preferably 0.1-0.5. The bottom operating temperature of the reactive distillation column is 70-130°C, preferably 80-110°C.

Example 1

Using the synthesis process of cycloethane carbonate shown in Figure 1, weigh 10g of ethylene glycol and 14.5g of dimethyl carbonate to prepare a raw material solution, mix it evenly, add it to the bottom of the reactive distillation column, and raise it to 70°C. 113 mg of potassium methoxide was added to start the reaction time. After 60 min of reaction, the liquid phase material was taken for qualitative and quantitative analysis by gas chromatography. The conversion rates of DMC and EG were 66.2% and 64.6%, and the selectivities of EC and ME were 92.2% and 99.8%, respectively. .

Example 2

Using the synthesis process of cycloethane carbonate shown in Figure 1, weigh 10g of ethylene glycol and 14.5g of dimethyl carbonate to prepare a raw material solution, mix it evenly, add it to the bottom of the reactive distillation column, and raise it to 60°C. 113 mg of potassium methoxide was added to start the reaction timing. After 15 min of reaction, the liquid phase material was taken for qualitative and quantitative analysis by gas chromatography. The conversion rates of DMC and EG were 66.8% and 65.2%, and the selectivities of EC and ME were 92.3% and 99.8%, respectively. .

Example 3

Using the synthesis process of cycloethane carbonate shown in Figure 1, weigh 10g of ethylene glycol and 14.5g of dimethyl carbonate to prepare a raw material solution, mix it evenly, add it to the bottom of the reactive distillation column, and raise it to 50°C. 113 mg of potassium methoxide was added to start the reaction time. After 15 minutes of reaction, the liquid phase material was taken for qualitative and quantitative analysis by gas chromatography. The conversion rates of DMC and EG were 64.6% and 65.3%, and the selectivities of EC and ME were 93.4% and 99.8%, respectively. .

Table 1 shows the activity evaluation of Examples 1-3 in the reactive distillation column, the molar ratio of dimethyl carbonate and ethylene glycol is 1, the catalyst is potassium methoxide (CH ₃ OK), and the amount of catalyst used is the same as that of dimethyl carbonate. The molar ratio of carbonate is 1:100, the reaction adopts total reflux, and the components in the column kettle are analyzed by gas chromatography.

Table 1. Composition of EG and dimethyl carbonate transesterification reaction products under different conditions

Examples 4-6

When the molar ratio of ethylene glycol and dimethyl carbonate was set as 1, the reflux ratio at the top of the column was 0.1, and the temperature at the column bottom was 78, 85, and 107.7°C, the equilibrium conversion rates of DMC were 80.2%, 86.8%, and 96.3%, respectively.

Examples 7-9

When the molar ratio of ethylene glycol and dimethyl carbonate was 1.5, the reflux ratio at the top of the column was 0.1, and the temperature at the column bottom was 85, 95.6, and 105°C, the equilibrium conversion rates of DMC were 93.5%, 97.5%, and 98.8%, respectively.

Examples 10-12

When the molar ratio of ethylene glycol and dimethyl carbonate was set to 2, the reflux ratio at the top of the column was 0.1, and the temperature at the column bottom was 96.6, 100, and 104°C, the equilibrium conversion rates of DMC were 98.3%, 98.7%, and 99.0%, respectively.

Table 2 shows the results of Examples 4-9.

Table 2. Results of transesterification to synthesize cycloethane carbonate

The foregoing description of the embodiments is provided to facilitate understanding and use of the invention by those of ordinary skill in the art. It will be apparent to those skilled in the art that various modifications to these embodiments can be readily made, and the generic principles described herein can be applied to other embodiments without inventive step. Therefore, the present invention is not limited to the above-mentioned embodiments, and improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should all fall within the protection scope of the present invention.

Claims (10)

1. A method for synthesizing the cyclic ethane carbonic ester is characterized in that dimethyl carbonic ester and ethylene glycol are used as raw materials, the cyclic ethane carbonic ester is synthesized by an ester exchange method, and a byproduct of methanol is generated.

2. The method for synthesizing the cyclic ethane carbonate as claimed in claim 1, wherein a reaction rectifying tower is used as a reaction site, dimethyl carbonate and ethylene glycol are subjected to ester exchange continuously in the reaction rectifying tower under the action of a catalyst, methanol is obtained at the tower top, and a mixture of the ethylene glycol, the cyclic ethane carbonate and the catalyst is extracted at the tower bottom.

3. The method for synthesizing the ethylene carbonate according to claim 2, wherein the reaction rectifying tower is divided into a first section, a second section and a third section from top to bottom, the first section is a rectifying section, the second section and the third section are reaction sections, the raw material ethylene glycol and the catalyst are fed between the first section and the second section, and the raw material dimethyl carbonate is fed between the second section and the third section.

4. The method for synthesizing cyclic carbonates according to claim 2, wherein the catalyst is an alkali metal alkoxide dissolved in ethylene glycol or methanol;

The alkali metal of the alkali metal alkoxide is sodium or potassium, and the alcohol is methanol, ethanol or glycol, preferably methanol or glycol.

5. The method for synthesizing the ethylene carbonate according to claim 2, wherein the molar ratio of the raw material ethylene glycol to the dimethyl carbonate entering the reactive distillation column is between 1.0 and 3.0, preferably between 1.3 and 2.0.

6. The method for synthesizing cyclic ethane carbonate according to claim 2, wherein the molar ratio of the alkali metal alkoxide to the ethylene glycol in the reactive distillation column is in the range of 1: 500 to 1: 50, preferably 1: 200 to 1: 100.

7. the method for synthesizing the cyclic ethane carbonate according to any one of claims 1 to 6, wherein the method specifically comprises the steps of:

(1) preparing a catalyst: dissolving the alkali metal alkoxide in raw material ethylene glycol or methanol to prepare a catalyst material;

(2) ester exchange reaction: respectively feeding the raw materials of ethylene glycol, dimethyl carbonate and catalyst material into a reaction rectifying tower through respective feeding pumps, obtaining cyclic ethane carbonate and methanol through catalytic ester exchange reaction, enabling the methanol to upwards enter a rectifying area under the rectifying action, enabling the methanol to enter the tower top, enabling the methanol to flow back through a condenser, obtaining high-purity methanol at the tower top, enabling the cyclic ethane carbonate to downwards enter the tower bottom, and forming a tower bottom material with excessive ethylene glycol and catalyst;

(3) And (3) catalyst recovery and circulation: the tower bottom material enters a film evaporator, ethylene glycol and cyclohexane carbonate are evaporated, the catalyst is concentrated and is sent to the catalyst preparation step through a catalyst circulating pump, and the catalyst is prepared into a catalyst material according to a proportion and recycled;

(4) separating and refining the cyclic ethane carbonic ester: feeding the ethylene glycol and the ethylene carbonate steam obtained in the step (3) into a separation and refining tower of ethylene carbonate, obtaining high-purity ethylene carbonate at the bottom of the tower, and obtaining ethylene glycol at the top of the tower;

(5) and (3) recycling the ethylene glycol: and (4) recycling the ethylene glycol obtained from the step (4) to the reaction rectifying tower for recycling.

8. The method for synthesizing cyclic ethane carbonate according to claim 7, wherein the reaction rectifying tower, the thin film evaporator and the cyclic ethane carbonate separation and purification tower are operated under reduced pressure.

9. The method for synthesizing ethylene carbonate according to claim 7, wherein the reflux ratio of the top of the rectifying tower is 0.1-1, preferably 0.1-0.5.

10. The method for synthesizing the cyclic ethane carbonate according to claim 7, wherein the operation temperature of the bottom of the reaction rectifying tower is 70-130 ℃, preferably 80-110 ℃.

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